1. Field of the Invention
This invention relates to a photoelectric cell designed for detection of an object, comprising an optical component equipped with a photosensitive area that generates an electrical reception signal on a conductor as a function of the incidence of an optical beam, and an amplification and processing circuit generating an output signal that depends on the electrical signal.
2. Discussion of the Background
A photoelectric cell is well known. When they operate by detection of a light flow originating from infinity without any proximity effect, they form par of a first family of cells called reflex, polarized reflex or barrage cells. When they operate by detection of light rays at high incidence, they form part of a second family of cells operating either by measurement of energy in a xe2x80x9cproximityxe2x80x9d subfamily, or by triangulation, comparing two channels of a PSD type component in a xe2x80x9cproximity with background eliminationxe2x80x9d subfamily. Detection modes for these two families will be referred to as xe2x80x9creflex modelxe2x80x9d and xe2x80x9cproximity modexe2x80x9d in the rest of this document, for simplicity. Cells in the first family are used particularly to detect the presence of an object, whereas cells in the second family are used particularly to detect the distance or brightness of an object.
The optical components necessary to make these two families are different. Their surface area is small, typically of the order of 0.6xc3x970.6 mm for reflex cells, but larger and typically with an apparent size 1.6xc3x971.6 mm for proximity cells or 1xc3x972 mm for proximity with background elimination cells. The result is that several types of components need to be procured and stored (typically at least three different components) in order to manage these two product families.
Furthermore, magnetic compatibility constraints affecting photoelectric cells are increasing, whereas the optical components that use them at the present time have the disadvantage that they offer low intrinsic amplification in the case of phototransistors, and even zero amplification in the case of photodiodes.
The purpose of this invention is to overcome these disadvantages by using simple arrangements that can be taken particularly on the optosensitive component or the processing circuit, so that it becomes easier to make a photoelectric cell insensitive to parasites and capable of operating in different operating modes in order to offer different detection possibilities.
According to a first aspect of the invention, the photoelectric cell comprises configuration means capable of acting on the photosensitive area or the processing circuit in response to a means of selecting a reflex operating mode or a proximity operating mode for the cell.
According to a second aspect of the invention, the photosensitive area is separated by separation into at least two adjacent partial areas isolated from each other, each of these partial areas being capable of supplying electric magnitudes to one of the two channels connected to the amplification and processing circuit, and configuration means are provided to select the operating mode specified for the cell; these configuration means are preferably capable of activating and/or processing electrical magnitudes output from the partial areas, for example by means of switches and/or a microcontroller, as a function of the selected operating mode.
Preferably, and when it is required to configure the cell in reflex mode and in proximity mode the adjacent partial areas are capable of outputting electrical magnitudes to a first conductor and a second conductor connected to the channel and configuration means are provided to activate the first conductor in reflex mode and the second conductor in proximity mode; the photosensitive area used in proximity mode may itself be separated by a demarcation transverse to separation, into isolated adjacent areas that are connected to the respective channels and the surface area of which varies continuously along the main direction of the component, this direction being the direction of displacement of the optical spot of the incident beam on the photoreceptive area in proximity mode.
Preferably, and when it is required to configure the cell in proximity mode or in proximity with background elimination mode, the photosensitive area used may be separated by demarcation transverse to the main direction, into isolated adjacent zones; the surface area of which varies continuously along the main direction of the component, which is an integrated component preferably comprising two amplifying parts of the amplification and processing circuit at the side of the photosensitive area, that amplify the signal originating form the partial areas or photosensitive zones and which are connected through the respective channels to a remaining part of the amplification and processing circuit that controls the configuration described above.